Updated

British forces battled more than 1,000 die-hard Iraqi loyalists for control of Basra on Wednesday, coming to the defense of inhabitants who rose up against Saddam Hussein in the streets of the country's second-largest city.

Inhabitants of the mostly Shiite Muslim city Tuesday started attacking members of Saddam's Baath Party and other Iraqi fighters, who responded by firing mortars at their own people, the British military said. The British, in turn, shelled the mortar positions and bombed Baath headquarters.

British Prime Minister Tony Blair, speaking in Parliament Wednesday, promised backing for the insurgents.

"Truthfully, the reports are confused, but we believe there was some limited form of uprising," Blair told the House of Commons. "It is important that we give support to those people in Iraq who are rising up to overthrow Saddam and his deeply repressive regime."

The uprising came as the British tried to gain control of Basra and relieve the city's trapped civilian population of 1.3 million, which was fast running out of food and was in danger of outbreaks of cholera and diarrhea from contaminated water.

Coalition forces have made no secret of their hopes to spur such uprisings in the strategic southern city.

"We are assessing the situation very carefully to see how we can capitalize on it and how we can assist," said British spokesman Group Capt. Al Lockwood.

During the battle for control of Basra, the Iraqis were firing artillery from the center of the city at British troops, said British spokesman Col. Chris Vernon, while the British confined their artillery to the city's outskirts, trying to identify clear military targets, especially tanks, and avoid civilian casualties.

"The bunch of desperados who've lived above the law rule the roost in this dictatorship, this regime that Saddam Hussein has been running," said Lt. Col. Ronnie McCourt, spokesman for British forces in the Persian Gulf. "They're obviously resorting to desperate measures and trying to intimidate the population, and we are making certain that we neutralize them as quickly as possible."

U.S. warplanes also dropped satellite-guided bombs on central Basra, targeting military sites hidden in civilian buildings, according to British accounts.

Gunner Neil Hughes of the Royal Horse Artillery said the Iraqis were using civilians as shields. "There's some tanks refueling -- five or six of them -- but we couldn't engage them because they were right next to a built-up area, a hospital," he said.

Britain's 7th Armored Brigade -- the famed Desert Rats -- was said to be awaiting orders to enter the heart of the city later Wednesday.

For days, coalition forces had hoped to avoid entering Basra for fear of getting bogged down in urban warfare. But tenacious resistance in the city -- there are an estimated 1,000 militia fighters, plus an unknown number of regular troops -- and fears for the trapped civilians led them to change their strategy.

During the 1991 Gulf War, Basra's Shiites rose up against Saddam's Sunni Muslim regime in Baghdad. Government forces crushed the rebellion, slaughtering thousands across the south.

On Tuesday night, thousands of Basra residents rampaged through the streets and set dozens of buildings ablaze, according to British reporters attached to military units.

"It appeared some of the population rose up and started attacking elements that are defending the city. These elements more and more as we're investigating them appear to be mostly criminal elements and ruling Baath party members," Lockwood said. "The attack from the local population obviously gave them cause for concern to the extent that they started mortaring them."

The exiled Iraqi National Congress opposition party called it a large uprising and said it involved fierce hand-to-hand combat and bayonets.

On Wednesday, McCourt said British forces were trying to prevent "these thugs and hoodlums" from trying to slip out of the city.

In a telephone interview with Al-Jazeera television, Iraqi Information Minister Mohammed al-Sahhaf denied there was an uprising in Basra.

"The situation is stable," he said. "Resistance is continuing and we are teaching them more lessons."

Defense Secretary Donald H. Rumsfeld said he was aware that Fedayeen guerrillas loyal to Saddam were infiltrating the city. But he said he was reluctant to encourage any uprisings.

"I guess those of us my age remember uprisings in Eastern Europe back in the 1950s when they rose up and they were slaughtered," he said. "We know there are people in those cities ready to shoot them if they try to rise up."

But he added: "Anyone who's engaged in an uprising has a whole lot of courage, and I sure hope they're successful."

The number of casualties in Basra was not immediately known. But the Arab TV network Al-Jazeera quoted Iraqi medics on Saturday as saying 50 people were killed in U.S. bombings there.

International relief agencies in phone contact with aid workers in the city expressed deep concern about the fate of trapped civilians.

"It's very alarming, very critical," said Veronique Taveau of the U.N. humanitarian office for Iraq.

The city's electricity was knocked out Friday during U.S.-British bombing. That in turn shut down Basra's water pumping and treatment plants. The U.N. Children's Fund estimated up to 100,000 Basra children under 5 were at immediate risk of severe disease from the unsafe water.